Pione vastifica (Hancock, 1849) is a red or orange-yellow excavating sponge, boring in mollusc shells. It may be recognized on its colour (light yellow in C. lobata) and small papillae (similar to C. lobata but much smaller than in C. celata), and microscopically on its unique possession of spined oxeas in addition to the usual tylostyles and spirasters. It occurs along most coasts of Western Europe from shallow-water down to 600 m.

Taxonomic Description

Colour:Red or orange-yellow.Shape, size, surface and consistency: Excavating mollusc shells and other calcareous objects. Papillae numerous, but quite small; often arranged in rows. Height about 0.5 mm. Inhalant papillae 0.2-0.4 mm in diameter, exhalant papillae 0.6-1.4 mm. Isolated shells may have up to 600 papillae depending on the species and size of the host; a single shell is normally occupied by a single sponge individual. Galleries (pione_vastifica_galleries.jpg) are thin, lobate (lobes up to 3 mm in diameter) and anastomosing to form complicated networks. Consistency soft. Spicules: Tylostyles, acanthoxeas and spirasters. Megascleres: Tylostyles with rounded head, straight shaft ending very gradually in a sharp point, 145-300 x 4-5 µm. Microscleres: Acanthoxeas, roughened or finely spined over their entire length, fusiform with curved tips, often centrotylote, quite variable in length, 60-160 x 2-7 µm. Spirasters, thin and small with feebly developed spines, undulated or almost straight, variable in length 6-23 x 1-4 µm.Skeleton:In the papillae the tylostyles are arranged in vertical columns and end in an ectosomal palissade. Interiorly, the spicules are in confusion. Acanthoxeas and spirasters numerous.Reproduction:Eggs are produced in late September. Asexual "gemmules" are found in the interior of the sponge most of the year.Ecology:In shells of bivalves, gastropods and barnacles, in corals, from the intertidal down to 600 m.Distribution:Scotland, Orkney, England, Ireland, Norway, Sweden, Denmark, Germany, France, N Spain; Western Mediterranean. Reported from other parts of the world ocean, but these very probably concern closely related, but different species.Etymology:vastificus (Latin) = making empty, making waste, referring to its excavating habit.Type specimen information:4 slides in the Hancock Museum, Newcastle-upon-Tyne, reg.no's 4.16.36-39, from Prestonpans, Scotland (Rützler and Stone, 1986).

Remarks

The colour and the tiny papillae enable recognition on sight. For definite discrimination from C. lobata microscopic examination is necessary (presence of acanthoxeas is diagnostic). The species is less destructive than C. celata, but may still inflict considerable damage to commercially exploited bivalve species. Recent research on the occurrence of P. vastifica in a population of Chlamys islandica has demonstrated that infestation in living shells may come close to 100 %, with noticeable effect on the growth rate of the host (Barthel et al., 1994). Source: Topsent, 1888a.

Stephens, J., 1917. Report on the sponges collected off the coast of Ireland by the dredging expeditions of the Royal Irish Academy and the Royal Dublin Society. Proc. roy. Irish Acad., 34 (B, 1): 1-16.